1. Field of the Invention
The present invention relates to a turret, for use on a machine tool, for mounting at least one rotating tool thereon and for rotating the rotating tool to machine a workpiece on the machine tool.
2. Description of the Related Art
Some machine tools, e.g., lathes, have a turret for mounting one or more rotating tools thereon and for rotating them with a drive motor to machine a workpiece on the machine tool. In the lathe, the turret has a swivel block mounted on a head thereof, and a plurality of tools including rotating tools and other machining tools are radially supported on the swivel block.
When the swivel block is swiveled about its own axis, a desired one of the supported tools (e.g., a rotating tool) is indexed to an indexed position (machining position). Then, the drive motor is energized to rotate the rotating tool about its own axis to machine the workpiece. The drive power or torque of the drive motor is transmitted to the rotating tool by a power transmitting mechanism including a belt, bevel gears and bearings.
Japanese laid-open patent publication No. 2003-251505, for example, discloses a tool turret, for use on lathes, for transmitting the drive power of a drive motor to a rotating tool on the turret through a power transmitting mechanism including bevel gears and bearings. The disclosed tool turret has a hollow swivel block which houses therein the bevel gears and bearings.
Published U.S. patent application No. 2004/0103510 discloses a tool turret having a drive motor disposed in a swivel drum. The drive motor is indirectly connected to a rotating tool mounted on the tool turret by a coupling mechanism (power transmitting mechanism) to rotate the rotating tool.
In the turret on the conventional lathes and on the lathe disclosed in Japanese laid-open patent publication No. 2003-251505, the drive motor is located in a position widely spaced from the rotating tool. Consequently, the power transmitting mechanism for transmitting the drive power from the drive motor to the rotating tool is relatively complex in structure. When the power transmitting mechanism is in operation, the belt, bevel gears, and bearings of the power transmitting mechanism generate heat and vibration. As a result, the power transmitting mechanism causes an energy loss, tending to lower the power transmitting efficiency and generate noise.
According to the tool turret revealed in Published U.S. patent application No. 2004/0103510, it is difficult to highly accurately assemble the drive motor onto a turret body through an opening, of the turret body, which provides easy access to the turret body. The coupling mechanism has a sensor and a mechanism for sliding a coupling. The sensor serves to detect a coupled state between the drive motor and a rotating tool. As a result, the coupling mechanism is of a complex structure, and it takes time for the coupling mechanism to connect and disconnect the drive motor and the rotating tool. Furthermore, a need has arisen to make it reliable to connect and disconnect the drive motor and the rotating tool.